Replacing all vacuam lines
 

1989 420sel: Should i use the same thin plastic vac.lines with the rubber connectors or is there a better alternitive?

The Mercedes type thin clear/white vac lines are the best. There are other types out there that are not as heat resistant, amd also pose a problem with collapsing under vacuum.
I just did ALL my vac lines, hoses and gaskets on a '83 500SEL (Grey Mkt same as '84 500 SEL).
Before doing so, I had one of those thin lines crack due to age and I used an alternative type hose and experienced the problem it caused. I was thankful I learned on the 1 temporary piece and not the whole job.
Know what they say, do it right the 1st time!

Thanks i will see if Fastlane has it.